Modeling precipitation and its effect on recrystallization during hot strip rolling of niobium steels

Using a physically based model, the microstructural evolution of Nb microalloyed steels during rolling in SSAB Tunnplåt’s hot strip mill was modeled. The model describes the evolution of dislocation density, the creation and diffusion of vacancies, dynamic and static recovery through climb and glide, subgrain formation and growth, dynamic and static recrystallization and grain growth. Also, the model describes the dissolution and precipitation of particles. The impeding effect on grain growth and recrystallization due to solute drag and particles is accounted for. During hot strip rolling of Nb steels, Nb in solid solution retards recrystallization due to solute drag and at lower temperatures strain-induced precipitation of Nb(C,N) may occur which effectively retard recrystallization. The flow stress behavior during hot rolling was calculated where the mean flow stress values were calculated using both the model and measured mill data. The model showed that solute drag has an essential effect on recrystallization during hot rolling of Nb steels.

Techno-economic Appraisal of Concentrating Solar Power Systems (CSP)

The diffusion of Concentrating Solar Power Systems (CSP) systems is currently taking place at a much slower pace than photovoltaic (PV) power systems. This is mainly because of the higher present cost of the solar thermal power plants, but also for the time that is needed in order to build them. Though economic attractiveness of different Concentrating technologies varies, still PV power dominates the market. The price of CSP is expected to drop significantly in the near future and wide spread installation of them will follow. The main aim of this project is the creation of different relevant case studies on solar thermal power generation and a comparison betwwen them. The purpose of this detailed comparison is the techno-economic appraisal of a number of CSP systems and the understanding of their behaviour under various boundary conditions. The CSP technologies which will be examined are the Parabolic Trough, the Molten Salt Power Tower, the Linear Fresnel Mirrors and the Dish Stirling. These systems will be appropriatly sized and simulated. All of the simulations aim in the optimization of the particular system. This includes two main issues. The first is the achievement of the lowest possible levelized cost of electricity and the second is the maximization of the annual energy output (kWh). The project also aims in the specification of these factors which affect more the results and more specifically, in what they contribute to the cost reduction or the power generation. Also, photovoltaic systems will be simulated under same boundary conditions to facolitate a comparison between the PV and the CSP systems. Last but not leats, there will be a determination of the system which performs better in each case study.

Spridning av innovation i högre utbildning : En studie av spridningen av Videochat vid Högskolan Dalarna

Syftet med denna uppsats har varit att beskriva och analysera spridningen av en innovation, Videochat, inom Högskolan Dalarna för att utifrån det lägga förslag på fortsatt arbete för att öka spridningen av Videochat. Frågorna som legat till grund för uppsatsen är: Vad är Videochattens spridningstakt inom Högskolan Dalarna? På vilka grunder har Videochat anammats inom Högskolan Dalarna? I de fall man inte har anammat Videochat, på vilka grunder man gjort det valet? Var och hur kan åtgärder sättas in för att stimulera spridningen av Videochat? Undersökningen har baserats på ett webbaserat frågeformulär bland Högskolan Dalarnas undervisande personal och frågorna i formuläret utarbetades med hjälp av förberedande intervjuer med nyckelpersoner inom Högskolan Dalarna. Undersökningen visar att användningen av Videochat har spridits olika långt på de olika akademierna och på två av fyra akademier anses det finnas ett behov av särskilda åtgärder för att stimulera spridningstakten. Den främsta anledningen till att börja använda Videochat är möjligheten att föreläsa för nätstudenter och campusstudenter samtidigt. Undersökningen visar samtidigt att anledningarna för att använda Videochat skiljer sig mellan de olika akademierna. Ett antal åtgärder föreslås för att stimulera spridning på de två akademier med lägst andel användare av Videochat där de viktigaste går ut på att öka kunskapen om Videochat och dess fördelar.

Organisationer, ojämlikhet, migration : förändringar av den etniska arbetsdelningen i svensk byggnadssektor

Organizations, Inequality, Migration – Changes of the Ethnic Division of Labour in the Swedish Construction Sector During the 1990s the number of migrants from Eastern Europe increased in the Swedish construction sector. This article examines how this change was initiated by changes in the organizational population in the construction sector. The gradual enlargement of the European Union changed the institutional framework for organizations in Sweden. This created increased opportunities for new organizational forms in the construction sector. The specific niche of the new organizations was to recruit and hire out workers from Eastern Europe that were paid lower wages than Swedish workers. The diffusion of this organizational form contributed to a change of norms and beliefs about what was legitimate and illegitimate when employing migrants. This implies that the inequalities that this organizational form introduces have gained increased legitimacy in Sweden. Or in other words, it has become increasingly socially acceptable to pay migrants lower wages than Swedish workers